Training & Nutrition - Weekly time at/above LT

At what point do I stop seeing cardio benefits from increasing time at or above lactate threshold? Would 2 hours/week result in adequate gains (assuming that I pad my mileage to, say, 10 hours/week at lower intensity) or would I benefit from more? And what is the level where I'd need to worry about overtraining?

I'm a relative novice, I've been training since March and my total mileage for the year so far is about 1500 miles.

At what point do I stop seeing cardio benefits from increasing time at or above lactate threshold? Would 2 hours/week result in adequate gains (assuming that I pad my mileage to, say, 10 hours/week at lower intensity) or would I benefit from more? And what is the level where I'd need to worry about overtraining?

I'm a relative novice, I've been training since March and my total mileage for the year so far is about 1500 miles.

I can't think of any reason why you'd want to spend so much time above your LTHR. I train about 12 hours per week on the bike, and probably no more than one hour of that is at or above my threshold - on the hills during longer rides, or during my once-a-week interval session. If you are spending less than ten hours a week on the bike, and two of those hours are above threshold, I'd say that is far too much. Increase your training volume, and spend more time at low and medium intensity. You need to build a base before you spend so much time on the top end.

Hmm. How about just below LT, day within 10 bpm? I would have to get out of my way just to cut higher intensity time to 2 hrs/week. It's mostly hills here, perhaps two thirds of my riding is uphill (time wise), and even moderate effort gets me within 5-10 bpm of LT.

Hmm. How about just below LT, day within 10 bpm? I would have to get out of my way just to cut higher intensity time to 2 hrs/week. It's mostly hills here, perhaps two thirds of my riding is uphill (time wise), and even moderate effort gets me within 5-10 bpm of LT.

That's an extremely beneficial training intensity. See here: http://www.fascatcoaching.com/sweetspottraining.html

To be honest, I've never seen a compelling, science-based argument to support the traditional high-volume, low-intensity approach. Granted, many pros supposedly train that way, but their conception of "high-volume" is very different from ours;)

Hmm. How about just below LT, day within 10 bpm? I would have to get out of my way just to cut higher intensity time to 2 hrs/week. It's mostly hills here, perhaps two thirds of my riding is uphill (time wise), and even moderate effort gets me within 5-10 bpm of LT.

How have you determined your LTHR? I wouldn't describe threshold as "moderate effort". It is, by definition, a level of effort that one cannot sustain indefinitely. That is why threshold training is usually undertaken in the form of blocks or intervals counted in minutes rather than hours.

I too will often go over my LTHR in the hills, or when doing intervals, but those efforts are usually of pretty short duration. And only a very severe hill will actually force me to do so, if I want to keep my HR below threshold I simply select a lower gear and slow down.

Training just below threshold is a different matter. One of my training sessions each week will be a level 3 "tempo" ride at about 85% of LTHR - in my case this has my HR in the high 130s. That ride will be maybe 90 minutes, two hours max.

EDIT: Hookflash is right about sweet spot training. But the sweet spot is below threshold, not above it. And my experience is that having banked a lot of time at lower intensities, one's ability to tolerate and recover from the zone 3 and 4 sessions is much enhanced.

I did a 30 min TT test about a month ago and got LT 162. I know that I can go for hours at 150-155 and I burn out after about 10 min at 170. So 162 sounds about right.
To my mind, 85% of 162 is low effort.

^^^ that was my comment

OK, let's not argue about what constitutes low or moderate effort, these are subjective terms anyway. Most of the coaching stuff I have read recommends tempo sessions at between 75% and 90% of threshold. 85% puts me squarely in the middle of HR zone 3 and that's pretty much where one derives the biggest aerobic bang for one's buck, as far as I know.

Anyway, we seem to be agreeing that just below LTHR is an effective place to train. I'd still contend that spending too much time above LTHR is counterproductive. Necessary, but if too prolonged it takes too long to recover from that session and probably compromises the training one can do in the succeeding days.

Trying to crunch the GPS data and extract time spent in different HR zones over the last two weeks. This is what I'm getting after excluding most stops (have to do it by hand, don't see an easy way to do this in Garmin Connect or Garmin Training Center):
Total time: 9h 50m per week
below 140 bpm: 39%
140..150 bpm: 20%
150..160 bpm: 31%
160..170 bpm: 10%
Above 170 bpm: 0% (~1 minute total in 2 weeks)

My max HR is somewhere around 190.

I'll have to try to vary these proportions and see how different loads work for me.